Field of Use
This disclosure is generally directed to ink jet transfix apparatuses and methods.
In particular, disclosed herein is a composition that improves the wetting and release capability of an aqueous latex ink in an ink jet printer.
Background
Inkjet systems in which a liquid or melt solid ink is discharged through an ink discharge port such as a nozzle, a slit and a porous film are used in many printers due to their characteristics such as small size and low cost. In addition, an ink jet printer can print not only paper substrates, but also on various other substrates such as textiles, rubber and the like.
During the printing process, various intermediate media (e.g., transfer belts, intermediate blankets or drums) may be used to transfer the formed image to the final substrate. In intermediate transfix processes, aqueous latex ink is ink jetted onto a transfer member or intermediate blanket where the ink film is dried with heat or flowing air or both. The dried image is subsequently transfixed on to the final paper substrate. For this process to operate properly, the transfer member or blanket has to satisfy two conflicting requirements—the first requirement is that ink has to spread well on the transfer member and the second requirement is that, after drying, the ink should release from the blanket. Since aqueous ink comprises a large amount of water, such ink compositions wet and spread very well on high energy (i.e., greater than 40 mJ/m2) hydrophilic substrates. However, due to the high affinity to such substrates, the aqueous ink does not release well from these substrates. Silicone rubbers with low surface energy (i.e., about 20 mJ/m2 or less) circumvent the release problem. However, a major drawback of the silicone rubbers is that the ink does not wet and spread on these substrates due to low affinity to water. Thus, the ideal transfer member for the transfix process would have both optimum spreading to form good quality image and optimum release properties to transfix the image to paper. While some solutions, such as adding surfactants to the ink to reduce the surface tension of the ink, have been proposed, these solutions present additional problems. For example, the surfactants result in uncontrolled spreading of the ink that causes the edges of single pixel lines to be undesirably wavy. Moreover, aqueous printheads have certain minimum surface tension requirements (i.e., greater than 20 mN/m) that must be met for good jetting performance.
Thus, there is a need for a way to provide the desired spreading and release properties for aqueous inks to address the above problems faced in transfix process.